The Projects were added to the Solution via "add | existing Project|...".
Our long-time goal is to fill the "ToolsProject" with completely stable modules etc while in the meantime every programmer has his own project to work in.
We already have a "SuperTools.cs" fie within the TooslProject where we keep our ...super tools

How would I access this class from usercode modules within, let's say, the "Programmer2_Project" (namespaces, etc.. )?

Note that once you make a reference in one direction, you can't then also make a reference in the opposite direction. This creates a cyclic redundancy (circular reference) that the compiler cannot handle. In your case, that means that your tools library cannot also contain a reference to your personal project.

This is not likely to happen in your case because of how you have the solution set up (I do the same, although I'm the only developer on our Ranorex automation), but I wanted to make this clear so you don't run into it in the future.